1. Field of the Invention
The present invention is related to a heat insulating cooking vessel utilized for a cooking process by which food semi-cooked by heating or cooling is kept warm or cool and brought to a completely cooked state.
2. Prior Art
In general, the process of heating and cooking food involves electrical heat or a direct flame. However, such a cooking process makes food susceptible to break-down or scorching due to heating, and consumes a large amount of energy.
A cooking process which can solve the above-mentioned problem is desirable, for example one in which vegetables or grains are immersed in a proper quantity of boiling water or boiling seasoned soup, or semi-cooked food is kept warm or cool for an extended period of time to bring it to a completely cooked state.
As a cooking vessel suitable for such a cooking process, the heat insulating cooking vessel shown in FIG. 11 has been conventionally proposed.
The heat insulating cooking vessel is composed of a heat insulating container 1, a container portion 3, an inner pot 2 releasably housed in the container portion 3, and a lid portion 4 disposed on the container portion 3, which can be sealed up.
The container portion 3 consists of an inner bottle 5 which is cylindrical and has an approximately hollow curve shaped bottom and an outer bottle 6 which has a larger diameter than that of the inner bottle 5 and has approximately the same shape as the inner bottle 5, both bottles being jointed airtight at their respective upper edges to form a dual wall structure. The space between the inner bottle 5 and outer bottle 6 is either a vacuum space or is filled with heat insulating material to form a heat insulating portion 7. A bottom element 8 is disposed on the bottom of the container portion 3, and handles 9, 9 are disposed on both sides of the container portion 3. The lid portion 4 is formed with an upper lid element 11 of an approximately disc shape and having a lid grip 10 at its center, and with a lower lid element 12 also of an approximately disc shape, the space between the upper lid element 11 and the lower lid element 12 being filled with heat insulating material.
An explanation is given of the inner pot 2 housed in the heat insulating container 1 referring to FIG. 12. The inner pot 2 is equipped with an inner pot container portion 13, an inner pot lid portion 14 and a hanger portion 15. On the upper edge of the inner pot container portion 13 is placed a disc-shaped inner pot container lid portion 14 with the same diameter as that of the container portion 13. Stopper portions 16, 16 are located on the outer peripheral wall of the inner pot container portion 13 so as to engage with the both ends of the hanger portion 15. The hanger portion 15, which is semi-circular shaped and has approximately the same diameter as that of the inner pot container portion 13, are rotatable with respect to the inner pot container portion 13.
FIG. 13 shows the structure of a rice cooker pot as disclosed in Japanese Patent Application Second Publication No. 62-44482. This rice cooker pot consists of a heat insulating pot 17 and a cooking pot 18 with a lid, which are housed releasably in the jar. The lid 19 is placed on the opening of the cooking pot 18 positioned flush or above the upper edge of the heat insulating pot 17. The lid element 20 filled with heat insulating material is positioned above the lid 19 of the cooking pot.
However, these conventional heat insulating cooking vessels have the following problems.
Referring to the heat insulating cooking vessel shown in FIG. 11, the hanger portion 15 of the inner pot 2 is disposed near the opening on the outer surface of the inner pot container portion 13, rotatable with respect to the container portion 13, and is circular with approximately the same curvature as that of the inner pot container portion 13. Therefore, when food is semi-cooked in the inner pot 2 prior to keeping the semi-cooked food warm or cool in the heat insulating container 1, the hanger portion 15 shifts its position relative to the inner pot container 13, thus making it difficult to stir the food in the pot 2. Furthermore, when the inner pot 2 is heated by a heating device such as a gas stove and the like, its heat is convected to the hanger portion 15, resulting in danger to a person who touches the hanger portion 15.
In addition, when the inner pot 2 is housed in the heat insulating container 1, the hanger portion 15, which is rotatable with respect to the container portion 13, may have the bottom portion of the inner pot container portion 13 touch the opening of the heat insulating container 1, so that the inner pot container portion 13 is tilted to cause food in the container to spill out.
Furthermore, when the inner pot 2 is housed in the heat insulating container 1 and cooking is performed by keeping the food either warm or cold, the hanger portion 15 is also housed in the heat insulating container 1. Therefore, the hanger portion 15 is heated, so that it is too hot for a person to touch, thus making it difficult to take the inner pot 2 out of the heat insulating container 1.
In addition, as the hanger portion 15 protrudes from the outer surface of the inner pot container portion 13, the dimensions of the heat insulating container 1 should be large to incorporate the protrusion, causing a higher production cost and preventing the cooking vessel from being lightweight and compact.
In the rice cooker pot shown in FIG. 13, as the lower surface of the lid element 20 is positioned above the upper edge of the heat insulating pot 17, or in other words, the insulating material 20a in the lid element 20 is positioned above the upper edge of the heat insulating pot 17, the insulating performance is reduced.
Furthermore, a structure in which no hanger is provided in the cooking pot (inner container) will reduce the ability to put in or take out the inner pot and to cook using the inner pot, unless the vessel is limited only to cooking rice, which is usually served directly from the inner pot.